Air tool



June 4, 1929. w, GREVE 1,716,049

AIR TOOL Original Filed Jan. 3. 1921 4 Sheets-Sheet l June 4, 1929. L,w, GREVE 1,716,049

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AIR TOOL OriginalFiled Jan. 5. 192] 4 Sheets-Sheet Z5 l vmfi ma w Jim; wy/M,

L. W, GREVE Junei4, 1929.

I 4 Sheets-Sheet 4 AIR TOOL Original Filed Jan. 3. 1921 l llll PatentedJune 4, 1929.

UNITED SATS LOUIS W. GREVE, OF CLEVELAND, OHIO, ASSIGNOR TO THECLEVELAND PN RUMATIO v were TOOL COMPANY, OF CLEVELAND, OHIO, ACORPORATION OF OHIO.

AIR TOOL.

Application filed January 3, 1921, Serial No. 434,500; Renewed May 10,1928.

This invention relates to rotary air tools such as drills of the typewherein power is transmitted to a rotary spindle through reciprocatingpistons and a crankshaft geared or otherwise connected to the spindle,and

'in certain respects the present invention is arrangement of valves forsupplying to and exhausting motive fluid from the two sets of cylindersWhich are arranged in V-formation, and to the means for actuating thevalves. Additionally the invention relates to the construction of thecrank-shaft including a novel arrangement of eccentric for actuating thevalves.

In general it may be stated that the object of the invention is to'increase the efiiciency'of, or power derived from pneumatic tools suchas drills, and especially to provide for quick passage of air from thesupply to the cylinders.

Briefly stated, the above results are accomplished very successfully byarranging the valve which controls the air for each set of cylinderscentrally or between the cylinders, thus providing a substantialequalization and also simplification of the air passageways. Preferablyreciprocating valves are employed, and these are actuated through themedium of an eccentric arranged on the crank-shaft between thecrankpins, the eccentric being formed by a peculiar and advantageousoffsetting of a part of the crank-shaft with reference to the bearingportions and crank pins thereof, the eccentric being preferablycounterbalanced near one end of the crankshaft so as to provide forsmooth operation.

The invention may be further briefly summarized as consisting in certainnovel details of construction, and combinations and arrangements ofparts which will be described in the specification and set forth in theappended claims. v

In the accompanying sheets of drawings wherein I have shown anembodiment of my invention which operates with high efficiency, Fig. 1is a longitudinal sectional View; Fig. 2 is a plan view with a part ofthe casing removed; Fig. 3 is .a transverse sectional view, the sectionbeing taken through one of the cylinders and cooperating piston of oneset, and through the centrally disposedvalve correspondingto the otherset of cylinders; Fig. 1 is a plan view of the crankshaft removed fromthe tool; and Fig. 5 is an end view of the same.

Referring now to the drawings, the easing or housing of the toolincludes a main casting 10 which forms the principal part ofthe housing,the housing being completed by a removable'cap 11 which is secured inplace by bolts 12 and forms part of the crank case, and by a removableendplate 13 which encloses the gearing connecting the rotary spindle tothe crank-shaft and constitutes a bearing for the spindle. The housingis provided with a pair of oppositely disposed sockets, 14: and 15 (seeFig. 1) adapted to receive handles, one of which will, as is customary,constitute the air supply or inlet and will be provided with .a

throttle valve. 1

The tool here shown is provided with two sets of cylinders 16, arrangedin 'V-formation, there being in this case fourcylinders in all, or twoin each set. The cylinders are in this instance arranged ninety, degreesapart. Furthermore, the cylinders of one pair are not directly opposite,buta're slightcisely like the rods-shown in my prior application alreadyreferred to, and are connected to the crank-shaft in the mannerexplained in my prior application; that is to say, each connecting rodis formed in one piece with a continuous ring 21 which surrounds thecrank pin of the crank-shaft, there being between each connecting rodring and the crank pin of the crank-shaft, a

series of balls 21 whose raceways or raceway grooves are formed directin the ring 21 and direct in the crank-shaft. In other words, separateraceway rings are avoided.

The crank-shaft to which power is transmitted by the connecting rods isshown at 22, this crank-shaft having several of the features ofconstruction which are believed to be novel with me, these featuresrendering cylinders and midway between them. The

two valve cylinders make the same angle with respect to each other as dothe two sets of main cylinders, namely, ninety degrees, and they areslightly staggered in conformityavith the staggering of the two sets ofmain or power cylinders.

Each valve cylinder has tightly fitted into it a ported bushing 24, (seeFig. 3), and each valve is in the form of a piston 25 which slides backand forth in the bushing, motion being transmitted from the crankshaftto the two valves 25 by connecting rods 26 having integral one-piecerings 27 engaging an eccentric of the crank-shaft to be presentlyreferred to.

Air is supplied through the handle which is connected to the socket toan air receiving chamber 28 of the housing'(see Figs. 1 and 3) and eachvalve controls the delivery of air from this chamber to the two workingcylinders associated with it. WVhile the details of the valve and theprecise arrange ment of the ports connecting each valve with the twoassociated working cylinders are not important to the present invention,in this instance air is delivered to the valve chamber of each valve bya port 29, and is delivered alternately to the two cylinders associatedwith the valve through ports 30 and 31. The exhaust takes place at theouter end 32 of the valve bushing 24, this end being covered by aperforated cap 33.

' With the valve in the position shown in Fig. 3, air is being deliveredfrom the port 29 by way of the valve to the port 31 which is connectedto the workingcylinder behind the valve or beyond the observer. At thesame time, air is exhausted from the port 30 direct into the outer end32 of the valve the port 29 through the valve chamber to the port 30,the port 31 will be brought into communication with the chamber 32 ofthe valve and the exhaust from this port will take place through theport 32 into the piston valve which is hollow,

to the outer end 32 of the bush-ing 24.

The point to be noted in passing is that the valve is located midwaybetween the two cylinders which it controls, and while the passagewaysconnecting the valve cham her to the two working cylinders may not beprecisely the same in length, they are substantially so, but at any ratethe necessity for long ports or passageways is with the presentarrangement entirely eliminated, and an increase of power decrease inair friction.

Taking up now the crank-shaft 22, it will be observed that thiscrank-shaft has ing portions 34 and 35 which are supported in ball andring bearings 36 and 37, which in turn are supported partly by-thehousing 10, and by crank case or cap 11. :One end of the crank-shaft,just beyond the bearing 37 has an integral pinion 38 which drives a gear39 which is fixed to a rotary tool spindle 40, whose axis is at thecenter of the housing, the axis being in the V between the two sets ofcylinders. This tool spindle which provided with the usual taperedsocket for a drill or other tool, has a bearing in a bushing 41, mountedin an outstanding boss of the end plate 13. The inner end of the spindleis reduced and has a bearing in the socketed end of a feed screw 42.

Additionally the, crank-shaft 22 has crank arms 43 extending from thebearing portions 34 and 35, and two crank pins 44 which arediametrically opposite, or one hundred and eighty degrees apart. Eachcrank pin 44 accommodates the rings of two connecting rods which extendto the pistons of two cylinders, one in one set and one in the oppositeset, these crank pins each having two ball race grooves 45 precisely" asdisclosed in my prior application.

Furthermore, this crank-shaft is provided between the crank pins 44, andabout centrally of the shaft lengthwise considered, with an eccentric 46for actuating the reciprocating. piston valves, this eccentric beingengaged by the rings 27 of the two rods 26 which are connected to thevalves.

The use of a single eccentric for actuating the two valves controllingtheair to both sets of cylinders is rendered possible by reason of thepeculiar location of the center of the eccentric 46 with reference tothe longitudinal axis of the crank-shaft. It will be observedparticularly by reference to Fig.5 that thecenter of the eccentric isoffset lateris obtained by the ally with reference to the center line oraxis of the crank-shaft, (i. e. the bearing portions thereof) and isalso offset angularly or circumferentially a few degrees, the crank arms47 which connect the eccentric to the crank pins 44 being offset ortwisted out of the plane of the crank arms 43. The location of thecenter of the eccentric with reference to the axis of thecrank-shaftand'the disposition of the crank arms 47 relative to thecrank arms 43 are readily apparent from Fig. 5.

Inasmuch as the crank-shaft has near the center an offset mass formed bythe eccentric and to an extent by the offset crank arms 47, it becomesnecessary in order to provide smooth operation and to minimize vibrationat high speed, to counterbalance this offset mass, and this I accomplishby the integral counterbalancing weight 48, located adj acent thebearing portion 35 and pinion 38 formed at one end of the crank-shaft.

The design of this crank-shaft 22 with its centrally located eccentricto actuate the valves located centrally with respect to the cylinders ofthe two sets presented still another problem in the way of minimizingthe number of parts and permitting the use of integral or one-pieceeccentric and connecting rod rings. In this connection it might bestated that in my prior application it is an important feature of theconstruction that the connecting rods have integral continuous oronepiece rings which surround the crank pins and are separated therefromby ball bearings whose race-ways are formed direct in the crank pin andin the connecting rod rings respectively, this being rendered possibleonly by a construction of the crankshaft such that the rings could bethreaded or slipped along the crank-shaft from one end thereof.

This same idea is carried into the present construction and applied tothe eccentric straps or rings 27, as well as to the connecting rodrings. That this might be accomplished it became necessary that theeccentric 46 and the annular shoulder 49 (that I prefer to provide atone side of the eccentric) be no greater in diameter than the insidebore of the connecting rod rings. Additionally to accomplish this, stillanother feature was necessary, that being the provision at the junctionof the arm 47 and the end of the eccentric opposite the shoulder 49 of astraight section 50 in line with the axis or center line of theeccentric, and of substantially the width of the eccentric straps orrings 27. To explain this, the connecting rod and eccentric or valve rodrings which engage respectively the two crank pins 44 and the eccentric46, are all slipped or threaded along the crank-shaft from the endhaving the bearing portions 34, i. e. the left hand end of thecrank-shaft, as the same is Viewed in Fig. 4. The rings of the twoconnecting rods which engage the crank pins remote from the bearingportion 34 are first slipped along the crank-shaft. Then the rings orstraps which engage the eccentric 46 are applied in a similar manner,and finally the rings of the connecting rods which engage the crank pinadjacent the bearing portion 34 are put into place. However, while theconnecting rod rings are separated from the crank pins by the sets ofball bearings, the rings or straps which engage the eccentric preferablyhave a plain fit on the latter, and inasmuch as loose play. between therings 27 and the eccentric must be reduced to a very small and almostnegligible amount, it is essential that in threading the eccentric ringsover the crank-shaft that the bore of these rings be brought into directalignment with the bearing formed by the eccentric 46 before they areslipped onto the eccentric. This is rendered possible by the provisionof the straight portion 50 in alignment with the eccentric at thejunction of the arm 47 and the end of the eccentric onto which the ringsare slipped.

A pneumatic tool constructed as explained above with the supply to andexhaust of air from the two sets of cylinders controlled by valvesarranged as described centrally with respect to the cylinders in the twosets, with the two valves actuated by an eccentric located between thecrank pins, with the rings which surround the crank pins and eccentriceach formed in one piece integral. with the connecting rods and withseparate race-way rings eliminated, is not only strong and durable, butby actual. test is found to have higher efliciency than similar tools asheretofore constructed, and this result in the way of increased power Iattribute partly to the minimizing of parts and reduction of mechanicalfriction, but chiefly to the location of the valves with the resultingre duction in the loss of air friction in the passage of the air to theworking cylinders, and to the efficient manner in which the valves areactuated by the single eccentric located between the crank pins andoffset as described with reference to the axis of the crankshaft.

Having described my invention, I claim:

1. In an air tool, a housing having a plurality of sets of cylindersarranged in V-formation, with opposite cylinders staggered, pistons inthe cylinders, valves between the cylinders, a crankshaft having offsetcrank pin portions and an. eccentric portion between the crank pinportions, a pair of connecting rods having integral rings arranged sideby side on each crank pin portion and connected centrally with pistonsin opposite cylinders, valve rods having integral rings arranged side byside on the eccentric portion and connected to the valves, the rings ofall said connecting rods and valve rods being adapted to be slipped overthe crank-shaft endwise thereof.

2. In an air tool, a housing having a plurality of sets of cylindersarranged in V-forn1ation, with opposite cylinders staggered, pistons inthe cylinder, valve cylinders between adjacent cylinders of each set,opposite valve cylinders being staggered,

valve pistons in the valve cylinders, a crankshaft having offset crankpin portions and an eccentric portion between the crank pin portions,a'pair of connecting rods having integral rings arranged side by side oneach crank pin portion and connected centrally with pistons in oppositecylinders,

-valve rods having integral rings arranged side by side on the eccentricportion and connected to the valve pistons, the rings of all of saidconnecting rods and valve rods being adapted to he slipped over thecrankshaft endwise thereof to their respective positions.

3. In an air tool, a housing having a plurality of sets of cylindersarranged in V-formation, with opposite cylinders staggored, pistons inthe cylinders, Valves between the cylinders, a crank-shaft having offsetcrank pin portions and an eccentric portion, a pair of connectingrods'having integral rings arranged side by side on each crank pin.portion and connected centrally with pistons in opposite cylinders,valve rods having integral rings arranged side by side on the eccentricportion and connected to the Valves, the rings of'all said connectingrods and valve rods being adapted to be slipped over the crank-shaftendwise there of, ball bearing races formed partly in the crank pinportions and partly in the rings, and ball bearings arranged in theraces. v

In testimony whereof, I hereunto afiiX my signature.

LOUIS W. GREVE.

